Tool assembly for manufacturing parts and a method of producing a tool assembly

ABSTRACT

A tool assembly and a method for manufacturing and sealing a tool assembly for manufacturing an article includes building a tool assembly using additive manufacturing or 3D printing processes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national stage of International ApplicationNo.: PCT/US21/30225, filed on Apr. 30, 2021, which claims the benefit ofU.S. Provisional Application No. 63/018,879, filed on May 1, 2020, theteachings of which are incorporated herein.

FIELD

The present disclosure relates to tooling for the manufacture of parts,and more specifically to a method of producing and sealing a toolassembly for manufacturing parts using a variety of processes.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

Equipment part manufactures are constantly searching for new ways toimprove product cycle time and shortening the product design process.When providing the best quality products for complicated assemblieshaving thousands of parts, multiple iterations of prototype orpreproduction builds are required.

In producing production level parts such as metal stampings or injectionmolded plastic parts, production level tooling and molds are expensiveand have very long build times. Thus, production level tooling and moldsare not a viable option when producing prototype or preproduction levelparts. Therefore, preproduction tooling is beneficial for producing alimited number of parts having nearly the same functionality. However,preproduction tooling still has long lead times that further prevent theacceleration of the preproduction process. Furthermore, although lessexpensive than production tooling, preproduction tooling is stillexpensive further applying pressure to the ability of reducing the costof the equipment manufacturing process.

While current preproduction tooling and molds have a variety of uses andperformance capabilities, they fail to further improve parts productionefficiency, costs, and product utility. Thus, while the current tooling,molds and processes are useful for their intended purpose, there is roomin the art for an improved tooling, molds, and manufacturing processesthat provides improved investment cost, build time, design flexibility,and quality.

SUMMARY

This disclosure describes a system and method for producing and sealingtool assemblies such as molds using additive manufacturing with highperformance plastic filament. Tool assemblies of the present disclosureare created using CAD (computer-aided design), and when necessary,cooling channels are strategically designed according to the model ofthe piece and the print orientation. Molds are three-dimensional (3D)printed using extrusion based additive printing out of one or morethermoplastic materials. The 3D printed tool assembly may includepost-processing such as computer numerical control (CNC) machining whennecessary to achieve Geometric Dimensioning and Tolerance (GD&T)standards according to the application. If cooling channels are includedin the tool assembly a viscous liquid sealant at high pressure isinfused into the cooling channels and cured to ensure the coolingchannels are gas and liquid tight at elevated pressures aboveatmospheric pressure. The system and method of the present disclosurecan be used to seal tool assemblies that may be used in a variety ofmanufacturing applications including but not limited to: stamping,foaming, injection molding, compression molding, resin transfer molding(and vacuum assisted), thermoforming, vacuum forming, investmentcasting, spin casting, and blow molding.

The present system and method have a high turn-around rate, beingproduced in one to two (1-2) weeks with lower cost than traditionalmetal tooling. This system and method is also relevant to a variety ofmanufacturing industries by supporting most tooling/molding methodsincluding stamping, foaming, injection molding, compression molding,resin transfer molding/vacuum assisted resin transfer molding,specifically for thermoset resins and filling preforms,thermoforming/vacuum forming, investment casting (as the preformsacrificial layer), spin casting, and blow molding.

The system and method of the present disclosure allows high designflexibility and by combining additive and subtractive manufacturing(when required), tools and molds will be produced faster and cheaperthan using conventional metal mold fabrication processes. This resultsin affordable molds even when used for low part quantities, designiterations, prototyping and creation of new models for product evolutionand innovation.

The system and method of the present disclosure is based on design formanufacturing (DFM) methods. This ensures total compatibility withadditive manufacturing fabrication, as well as ease of assembly with thehardware that will form part of the mold for its incorporation into aninjection molding machine or other mold forming machines.

The system and method of the present disclosure can be adjusted to matchany commercial molding machine hardware.

The system and method of the present disclosure seals the tool assemblyto be compatible with pressurized coolant systems and it is suitable tobe used in industrial machines.

The system and method of the present disclosure uses high temperaturethermoplastic materials employing additive manufacturing. This isbeneficial because thermoplastic materials are less expensive and easierto work with than metals in the formation of tool assemblies and molds.The materials and use of additive manufacturing also allow for easyreplication.

The system and method of the present disclosure is initiated usingcomputer assisted design (CAD) software to create a model. The model canbe designed with or without cooling channels depending on the toolingpurpose. Once the model is complete, it is imported into a slicingsoftware used to generate the extrusion based additive printing pathwith specific print settings according to the material, including printtemperature, print speed, print extrusion, layer height and width. Thisis referred to as a G-code which is then transferred to a 3D printercapable of printing the volume of the part. Depending on the materialused, the 3D printer must have a heated bed and a heated build volume.

Upon completion, the printed part is removed from the 3D printer.Post-processing steps may then be used to complete the tool assembly ofthe present disclosure. Sacrificial (support/base/brim/skirt/raft)material may be first removed by a computer numerical control (CNC)machine. If cooling channels are designed into the tool assembly, entryand exit ports of the cooling channels are cleaned and may be tapped toallow threading of coolant connectors and hosing.

Polymer extrusion 3D printing produces parts, tool assemblies or moldshaving many material layers which are generally not moisture resistant,as individual layers can absorb moisture, form voids between successivelayers and therefore leak coolant. Coolant leakage may subsequentlyresult in tool assembly failure from coolant loss and tool assemblyoverheating or if the coolant leaks into the tool assembly rendering thetool assembly dysfunctional. The system and method of the presentdisclosure therefore further infuses a sealant into the 3D printed partto create a tool assembly that can withstand pressurized coolant withoutleaking.

The process to infuse sealant into the tool assembly requires preheatingthe tool assembly followed by introduction of a flowable material at acontrolled rate to minimize formation of bubbles, with the flowablematerial initially filling the cooling channels. Once the coolingchannels are full, the cooling channels having the sealant fluid arepressurized inside the tool assembly to a pressure ranging betweenapproximately 60 psi to approximately 100 psi and up to approximately150 psi and held at pressure for a minimum of 60 seconds. After theseinfusion and pressurization steps, residual sealant fluid is removedfrom the cooling channels by positioning the tool assembly on a spintable and rotating the tool assembly to centrifugally remove residualsealant from the tool assembly cooling channels to ensure no coolingchannels or coolant ports are clogged with residual fluid. The flowablesealant material remaining in the cooling channels is then set or curedusing a curing process. It is noted if any one or all of the coolingchannels for a tool assembly design are not needed, a small diameterhole may be tapped into a side or edge of the tool assembly and filledwith the flowable sealant material for added support and functionality.

An additional option for sealing the tool assembly is electroplating andpolishing. This can be accomplished using an electroplating compatiblethermoplastic material or by using a multi-step process that will allowelectroplating of an outer tool assembly surface. The electroplating ison the tool assembly surface. An additional buffing step may then beapplied help achieve a class A finish. Electroplating if used providesboth the class A surface needed for automotive and other industries aswell as mechanical property enhancement.

Once the sealing process is complete, the tool assembly is ready foruse. Materials that can be used for the infusion/sealing process includebut are not limited to high flow, high temperature stability two-partepoxies, ceramics (flowable), and electroplating materials.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a side elevational view of a tool assembly half formanufacturing an article using a plastic injection molding processaccording to the principles of the present disclosure;

FIG. 2 is an end elevational view of the tool assembly for manufacturingan article of FIG. 1 ;

FIG. 3 is a partial cross-sectional view of the tool assembly fromsection 3 of FIG. 2 ;

FIG. 4 is a cross-sectional view of a tool assembly from section 4 ofFIG. 1 ;

FIG. 5 is an end elevational view similar to FIG. 2 of a tool assemblyhaving an exemplary cooling channel with multiple flow bends;

FIG. 6 is side elevational perspective view of the tool assembly of FIG.5 positioned on a rotary spin table;

FIG. 7 is a flowchart depicting a method of manufacturing a toolassembly according to the principles of the present disclosure;

FIG. 8 is a cross-sectional end elevational view of an exemplary coolingchannel following deposition of a layer of sealant; and

FIG. 9 is a block diagram illustrating an example computing deviceaccording to the principles of the present disclosure.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring now to FIGS. 1 and 2 , a mold or a tool assembly 10 for use ina blow molding process is illustrated and will now be described. Thetool assembly 10 or a similar mold or tool assembly may alternatively beused in another type of manufacturing process without departing from thescope of the present disclosure. The tool assembly 10 includes a firstor upper half 12, a second or lower half 14, and a temperature controlsystem 16. More particularly, the upper and lower halfs 12, 14 of thetool assembly include at least one part-cavity 18 and a plurality ofcooling channels 20 in communication with the temperature control system16. The cooling channels 20 are arranged to provide the most consistentoperating temperatures possible in the tool assembly 10. For example,since the cooling channels 20 are printed by a 3D printer, the varietyof shapes, sizes, and cross sections of the cooling channels 20 that canbe built is much greater than cooling channels in traditionally machinedtool assemblies. The flow rate of coolant through the cooling channelscan be varied by altering the cross section of a particular coolingchannel 20. Cooling channels 20 can even be printed to produce heattransfer effects that have not been possible in prior tool assemblybuilding methods.

Referring now to FIG. 3 , a cross section of the surface 22 of a coolingchannel 20 from the tool assembly shown in FIG. 2 is illustrated andwill now be described. Being that the tool assembly is built using a 3Dprinting or additive process, the tool assembly is predominantly createdby layers 24 that are fused together that produce some voids orvacancies 26 between the layers 24 that may not have fused togethercompletely. The surface 22 further includes a pressurized and curedsealant 28 that extends between the layers 24 and coats the surface 22thus providing a passage that can withstand high pressure andtemperatures without yielding. In the present example, the sealant is atwo-part high temperature cured epoxy. However, other types of sealantsmay be incorporated into the tool assembly 10 without departing from thescope of the present disclosure.

Referring now to FIG. 4 , a cross section of the surface 30 of a partcavity 18 from the tool assembly shown in FIG. 1 is illustrated and willnow be described. Being that the tool assembly is built using a 3Dprinting or additive process, the tool assembly is predominantly createdby layers 24 that are fused together that produce some voids orvacancies 26 between the layers 24 that may not have fused togethercompletely. Furthermore, depending upon the thickness of the layers 24,some applications may require additional machining to achieve requiredshapes and tolerances. For example, the surface 30 is shown having beenCNC machined to achieve the specified shape of the tool cavity 18. Thesurface 30 further includes a pressurized and cured sealant 28 thatextends between the layers 24. Additionally, in some applications, oncethe surface 30 is sealed a layer of deposited metal 32 may be includedto provide for improved wear resistance, impact strength, and surfacefinish.

Referring to FIG. 5 , according to several aspects, a tool assembly 34of the present disclosure includes a mold or tool assembly body 36having an exemplary cooling channel 38 similar to the cooling channel20. The cooling channel 38 includes at least one and according toseveral aspects multiple flow bends 40, 42, 44, 46, 48, 50, 52, 54between a flow inlet port 56 and an outlet port 58.

Referring to FIG. 6 , after infusion of the sealant into the coolingchannel 34 as described below in reference to FIG. 7 , the tool assembly34 is placed proximate to a center of a spin table 60. A motor 62connected to the spin table 60 is energized to rotate the spin table 60,for example in a clockwise direction of rotation 64. Rotation of thespin table 60 generates centrifugal forces on the tool assembly 36 whichact to push excess sealant out of the cooling channels 38. It is notedthe spin table 60 provides an exemplary source of centrifugal force andmay be replaced by any device or system that generates centrifugalforces on the tool assembly.

Referring to FIG. 7 , a method 100 is depicted for creating the toolassemblies of the present disclosure such as the tool assembly 10described in reference to FIG. 1 or the tool assembly 34 described inreference to FIG. 5 for use in the manufacture of parts using a varietyof manufacturing processes. Portions of the method 100 may be carriedout by a processor of one or more computing devices, such as a computingdevice described in connection with FIG. 9 , for example. The method 100described herein is for creating a tool assembly for use in a plasticinjection mold process. However, many other types of tool assemblies foruse in many other manufacturing processes may be built using the method100 described herein. For example, tool assemblies or mold assembliesmay be built for metal stamping, foaming, injection stretch blowmolding, compression molding, metal casting sand core making, resintransfer molding, thermoforming, investment casting, spin casting, andblow molding without departing from the scope of the present disclosure.

The method 100 includes a first step 102 of making a CAD model ofsurfaces of a tool assembly such as the tool assembly 34. The CAD modelmay be created by using a surface scanning tool that uses a lasermeasuring device to convert the surface of a solid master part modelinto digital surface data. The CAD model may also be created partiallyfrom a CAD model of a desired part. Once the CAD model of the surface orsurfaces of the tool assembly is created, a second step 104 addsfeatures to the surface data including but not limited to tool designfeatures such as parting surfaces, cooling channels, ejection pin holes,vent holes, and injection passages, thereby creating a CAD model of thetool assembly.

Next, a third step 106 uses a conversion or slicing software andgenerates a printing path of the CAD model of the tool assembly andtransfers the printing path to a 3D printer. In a fourth step 108 asolid model of the tool assembly is printed using a 3D printer. In someapplications, the 3D printing process includes using a high temperature,high performance thermoplastic filament that produces a high strengthprinted part capable of sustaining high stresses and high temperaturemanufacturing processes. Other 3D printing materials and processesintended to increase the strength and durability of the solid model ofthe tool assembly may also be used without departing from the scope ofthe present disclosure.

Following generation of a G-Code, in a fifth step 110 a G-Code isoptimized using a programming script such as but not limited to, apython script, to optimize multiple items, for example a minimum or aleast amount of travel moves is developed. In a sixth step 112 a singleseam line of the tool assembly is identified and optimized. In a seventhstep 114 a plurality of varying temperatures of the tool assembly areoptimized based on infill of printed parts versus outlines of theprinted parts. The above optimizations are performed to obtain a bestfinish of the 3D printed part made using the tool assembly and to obtaina highest strength of the 3D printed part.

In an eighth step 116 the tool assembly is heated in an oven atapproximately 70 degrees C. for approximately 4 hours, which allows thetool assembly to rid thermally induced mechanical stresses and toprevent formation of further voids, gaps and pores. The tool assembly isthen taken out of the oven.

In a ninth step 118 while the tool assembly is still at or near oventemperature a sealant is poured into any cooling channels such as thecooling channels 20, 38 with the elevated temperature of the toolassembly 34 allowing the sealant to begin curing as quickly as thesealant comes into contact with surfaces inside the tool coolingchannels 38. Rapid curing also allows the sealant proximate to the toolcooling channel surfaces such as surfaces described in reference toFIGS. 3 and 4 to immediately increase in viscosity to improve coating ofthe sealant. According to several aspects, a preferred sealant is one ofa high flow, high temperature two-part epoxy and a flowable ceramichowever, other flowable, curable sealants may be used without departingfrom the scope of the present disclosure.

In a tenth step 120 the sealant is pressurized to force the sealant intogaps or crevices defining voids of the cooling channel walls. Inparticular, the cooling channels 38 are filled with the sealant which ispressurized to a pressure ranging between approximately 60 psi up toapproximately 100 psi for a pressurization period of 30 seconds or moreand preferably at least 60 seconds. According to several aspects, thepressure applied to the cooling channels 38 may be approximately 150 psifor approximately 60 seconds to force the sealant to flow into the gapswithin the cooling channels 38 to fill the gaps and the cooling channels38 more completely.

After the pressurization period is completed and the pressure on thesealant is released, in an eleventh step 122 a centrifugal force isapplied to the tool assembly to remove excess sealant from the toolassembly. According to several aspects the tool is placed proximate to acenter of the spin table 60 described in reference to FIG. 6 and themotor 62 is energized to rotate the spin table 60. The motor 62 whenenergized generates centrifugal forces on the tool assembly 34 which actto push excess sealant out of the cooling channels 38. According toseveral aspects the spin table 60 may be rotated at a rotationalvelocity between approximately 75 rpm up to approximately 125 rpm for aminimum of 3 minutes, however other rotational speeds and spin durationsmay be selected. Rotation of the spin table 60 forces portions of thesealant that does not coat the cooling channels 38 out of the coolingchannels 38 and therefore out of the tool assembly 34. It is noted thetool assembly 34 may be positioned in one or multiple differentpositions and orientations on the spin table 60. This allows centrifugalforces to be applied on the tool assembly in multiple planes of rotationand orientations to displace the excess sealant. As noted herein, thespin table 60 provides an exemplary source of centrifugal force and maybe replaced by any device such as but not limited to a shaft or a tooltumbler that generates centrifugal forces on the tool assembly inmultiple planes of rotation and orientations.

The residual heat maintained in the tool assembly 34 during the spinningstep following removal from the oven helps to retain the sealantcaptured in the gaps and on the cooling channel surfaces of the coolingchannels 38 due to increased viscosity of the sealant at the elevatedtool assembly temperature. The increased viscosity sealant is therebyallowed to better bind to the tool assembly 34.

Referring to FIG. 8 and again to FIGS. 1 through 4 , an exemplary layer124 of remaining sealant is created along an inner wall 126 of thecooling channel 20 including sealant that has been infused into thevoids of the cooling channel walls referred to in FIGS. 3 and 4 as theresidual sealant is removed from the cooling channel 20. According toseveral aspects the layer 124 of remaining sealant may have a thickness128 of approximately 3.0 mm, and may range in thickness fromapproximately 1.0 mm up to approximately 10.0 mm. According to furtheraspects, a second layer of the sealant may be applied if desired tobuild up the thickness 128 to a desired value. The thickness 128 mayvary based on an initial temperature of the tool assembly and a spin rpmor centrifugal force applied using the source of centrifugal force. Theremaining sealant may be cured in place as follows. The tool assembly isremoved from the spin table 60 or the source of centrifugal force andleft to cool completely to atmospheric temperature, for exampleover-night or for a period of approximately 8 or more hours. Thiscooling period permits the remaining sealant to cure completely.

FIG. 9 illustrates an example computing device 200. The computing device200 can include a processor 202, a memory 204, and a communicationmodule 206.

The processor 202 provides processing functionality for the computingdevice 200 and may include any number of processors, micro-controllers,or other processing systems, and resident or external memory for storingdata and other information accessed or generated by the computing device200. The processor 202 may execute one or more software programs whichimplement techniques described herein. The processor 202 is not limitedby the materials from which it is formed or the processing mechanismsemployed therein and, as such, may be implemented via semiconductor(s)and/or transistors (e.g., electronic integrated circuits (ICs)), and soforth.

The memory 204 is an example of tangible computer-readable media thatprovides storage functionality to store various data associated with theoperation of the computing device 200, such as the software program andcode segments mentioned above, or other data to instruct the processor202 and other elements of the computing device 200 to perform the stepsdescribed herein. Although a single memory 204 is shown, a wide varietyof types and combinations of memory may be employed. The memory 204 maybe integral with the processor 202, stand-alone memory, or a combinationof both. The memory may include, for example, removable andnon-removable memory elements such as RAM, ROM, Flash (e.g., SD Card,mini-SD card, micro-SD Card), magnetic, optical, USB memory devices, andso forth.

The communication module 206 provides functionality to enable thecomputing device 200 to communicate with one or more communicationnetworks. In various implementations, the communication module 206 maybe representative of a variety of communication components andfunctionality including, but not limited to: one or more antennas; abrowser; a transmitter and/or receiver (e.g., radio frequencycircuitry); a wireless radio; data ports; software interfaces anddrivers; networking interfaces; data processing components; and soforth.

The computing device 200 can be communicatively connected to a surfacescanning tool 208 and a 3D printer 210. In some example implementations,the computing device 200 can receive data representing a CAD model fromanother computing device via the one or more communication networks.

The description of the present disclosure is merely exemplary in natureand variations that do not depart from the gist of the presentdisclosure are intended to be within the scope of the presentdisclosure. Such variations are not to be regarded as a departure fromthe spirit and scope of the present disclosure.

What is claimed is:
 1. A method comprising: receiving a tool assemblyincluding a plurality of layers defining at least one part-cavity andplurality of cooling channels; pouring sealant into the plurality ofcooling channels; pressurizing the sealant to a pressure for apressurization period; and applying a centrifugal force to the toolassembly to remove excess sealant from the tool assembly, wherein thesealant extends between the plurality of layers.
 2. The method asrecited in claim 1, further comprising: heating the tool assembly in anoven at approximately seventy degrees Celsius for approximately fourhours.
 3. The method as recited in claim 2, further comprising: pouringthe sealant into the tool assembly while the tool assembly is at or nearseventy degrees Celsius.
 4. The method as recited in claim 3, whereinthe sealant is pressurized to a pressure ranging from approximatelysixty pounds per square inch to approximately one hundred pounds persquare inch.
 5. The method as recited in claim 4, wherein thepressurization period comprises at least thirty seconds.
 6. The methodas recited in claim 4, wherein the pressurization period comprises atleast sixty seconds.
 7. The method as recited in claim 3, wherein thesealant is pressurized to at least one hundred and fifty pounds persquare inch for a pressurization period of at least sixty seconds. 8.The method as recited in claim 7, wherein the tool assembly is rotatedat a rotational velocity between approximately seventy-five revolutionsper minute up to approximately one hundred and twenty-five revolutionsper minute for at least three minutes.
 9. The method as recited in claim1, wherein the sealant comprises a two-part epoxy and flowable ceramicmaterial.
 10. A method comprising: receiving a tool assembly including aplurality of layers defining at least one part-cavity and plurality ofcooling channels; pouring sealant into the plurality of coolingchannels; pressurizing the sealant to a pressure for a pressurizationperiod; and applying a centrifugal force to the tool assembly to removeexcess sealant from the tool assembly at a rotational velocity betweenapproximately seventy-five revolutions per minute up to approximatelyone hundred and twenty-five revolutions per minute for at least threeminutes, wherein the sealant extends between the plurality of layers.11. The method as recited in claim 10, further comprising: heating thetool assembly in an oven at approximately seventy degrees Celsius forapproximately four hours.
 12. The method as recited in claim 11, furthercomprising: pouring the sealant into the tool assembly while the toolassembly is at or near seventy degrees Celsius.
 13. The method asrecited in claim 12, wherein the sealant is pressurized to a pressureranging from approximately sixty pounds per square inch to approximatelyone hundred pounds per square inch.
 14. The method as recited in claim13, wherein the pressurization period comprises at least thirty seconds.15. The method as recited in claim 13, wherein the pressurization periodcomprises at least sixty seconds.
 16. The method as recited in claim 12,wherein the sealant is pressurized to at least one hundred and fiftypounds per square inch for a pressurization period of at least sixtyseconds.
 17. The method as recited in claim 10, wherein the sealantcomprises a two-part epoxy and flowable ceramic material.
 18. A toolassembly, comprising: an upper half defining at least one part cavityand a plurality of cooling channels; and a lower half defining at leastone part cavity and a plurality of cooling channels, wherein eachcooling channel of the plurality of cooling channels defines a surfacethat includes a pressurized and cured sealant extending between one ormore layers and that coats the surface.
 19. The tool assembly of claim18, wherein the sealant comprises a two-part high temperature curedepoxy.
 20. The tool assembly of claim 18, wherein the plurality ofcooling channels are configured to connect to a temperature controlsystem.